1. Field of the Invention
The present invention relates to a socket for a printed circuit board which serves as a connector for allowing the edge of the printed circuit board to be directly inserted therein as a plug section and, in particular, a socket for allowing a plurality of printed circuit boards to be mounted therein.
2. Brief Description of Prior Developments
In recent years, there has been a growing demand for high-density integration packages and various low insertion force type connectors have been developed.
Generally, such a low insertion force type connector serves as a socket mounted on a substrate of an electronic device, that is, a so-called mother board, and comprises a housing of an insulating material. The housing has an insertion slot for allowing the edge of a printed circuit board called "a daughter board to be received therein. The housing has an array of spring contacts therein with the contact sections of the spring contacts projected in the insertion hole for the printed board. These contacts are formed as two contact arrays along the longitudinal direction of the insertion hole and a gap is created between these contact arrays to receive the edge of the printed circuit board therein. The contact arrays are arranged, in an offset state, in the depth direction of the insertion slot, that is, along the insertion direction of the printed board. When, therefore, the printed circuit board is inserted, it is contacted at one surface side of its edge with the contact array in a position near the forward end of the edge of the printed board and at the other surface side with the associated contact array in a position remote from the position above.
When the edge of the printed board is inserted between the contact arrays and the printed board is rotated in a direction to cause these contact arrays to be displaced away from each other, the contact sections of the spring contacts are displaced by a spring force trying to bring the contact sections of the spring contacts back to their original position, the respective contacts are placed in positive contact with associated conductors arranged at the edge of the printed board.
The printed board is held in a rotated position by a latch mechanism and positively fixed to the housing while maintaining a better contact state between the respective contacts and the printed board.
The conventional socket serving as such a low insertion force type connector has only one insertion hole and, if a plurality of printed boards are required, it is necessary to provide a corresponding number of sockets.
In the case where a plurality of printed boards are mounted on the housing, more space is required and it is, therefore, difficult to obtain such an electronic device as a compact and low cost unit.